1. Field of the Invention
The present invention relates to a drive for a vehicle. More particularly, the present invention relates to a drive for a vehicle intended to traverse rough terrain
2. Description of the Prior Art
Numerous innovations for obstacle traversing drives have been provided in the prior art that will be described. Even though these innovations may be suitable for the specific individual purposes to which they address, however, they differ from the present invention.
FOR EXAMPLE, U.S. Pat. No. 4,674,757 to Martin teaches a wheel for use with a variety of devices for moving a load up or down a series of stairs. The wheel is comprised of a plurality of lobe-like teeth on a gear. Each lobe has two surfaces which are symmetrical around a lobe center line, with each surface being made up of a portion of an involute curve defined by a circle having a particular radius. The involute curves making up the surfaces of each lobe mirror each other on opposite sides of the center line and intersect to form the lobe at the largest radii of the portions of the involute curves making up the surfaces of the lobe. The wheel may be made to specifications allowing exact fit on a particular size stair step and a properly fitting wheel will move in a close approximation of a straight line parallel to the staircase incline as it moves up a flight of stairs.
ANOTHER EXAMPLE, U.S. Pat. No. 4,747,611 to Daugherty Jr. teaches selectively operable spiral cam wheels that are positioned adjacent and rotate on a common axis with the drive wheels and are attachable to the drive wheels for progressively raising the wheelchair in response to rotation of the drive wheels in one direction and for progressively lowering the wheelchair in response to rotation of the drive wheels in the opposite direction. The spiral cam wheels are also attachable to the wheelchair frame so that the drive wheels are free to be rotated in the normal manner. A lifting arm is pivotally supported at one end on each side of the frame of the wheelchair and the other end is moved by the spiral cam wheels to progressively lift the casters of the wheelchair as the wheelchair is moved toward a curb to be traversed. Embodiments of the wheelchair are disclosed in which the wheelchair is raised as it is moved in a forward direction toward the curb, and in which the wheelchair is raised as it is moved in a rearward direction toward the curb.
STILL ANOTHER EXAMPLE, U.S. Pat. No. 5,273,296 to Lepek teaches a suspension for propelling a vehicle so as to overcome an obstruction in its desired path of progress. The suspension includes connections between the chassis and body of the vehicle with its wheels or wheel like elements. A cam guides the rollers to overcome obstructions in the vehicle""s path.
YET ANOTHER EXAMPLE, U.S. Pat. No. 5,881,831 to Harvey teaches a multi-terrain amphibious vehicle adapted for travel across surfaces of various type and attributes. The vehicle includes a chassis assembly which extends in a longitudinal direction; a plurality of propulsion members rotatably coupled to the chassis assembly for propelling the vehicle across a given surface; and, a control mechanism for controlling the rotational velocities and phases of the propulsion members. The propulsion members each rotate about axis that extends in a direction substantially normal to the longitudinal direction. Each propulsion member includes, for engaging the given surface, at least a first perimeter segment and a second perimeter segment coaxially disposed in angularly offset manner about its rotation axis. The first perimeter segment has an arcuate contour and extends radially farther from the rotation axis than does the second perimeter segment. In operation, the propulsion members are cooperatively rotated to collectively impart a predetermined speed and direction of travel to the vehicle.
It is apparent that numerous innovations for obstacle traversing drives have been provided in the prior art that are adapted to be used. Furthermore, even though these innovations may be suitable for the specific individual purposes to which they address, however, they would not be suitable for the purposes of the present invention as heretofore described.
ACCORDINGLY, AN OBJECT of the present invention is to provide a drive for a vehicle intended to traverse rough terrain that avoids the disadvantages of the prior art.
ANOTHER OBJECT of the present invention is to provide a drive for a vehicle intended to traverse rough terrain that is simple to use.
BRIEFLY STATED, STILL ANOTHER OBJECT of the present invention is to provide a drive for a vehicle traversing rough terrain including first and second drive units and first and second pairs of tires. The first drive unit includes a first differential and axle. The second drive unit includes a second differential and axle. A secondary drive shaft synchronizes the second and first differentials. Each tire is divided into first and second segments. The center of the first segment is the rotational center of the tire so as to allow it to roll when in contact with the rough terrain. The first segment extends 240xc2x0 and the second segment extends 120xc2x0. The radius of curvature of the second segment is greater than that of the first segment so as to allow it to be only slightly curved and almost flat, and as a result thereof, pointed areas are formed that bite into, and allow the second segment to grip, the rough terrain.
The novel features which are considered characteristic of the present invention are set forth in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best from the following description of the specific embodiments when read and understood in connection with the accompanying drawing.